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Q: Fachverband Quantenoptik und Photonik

Q 48: Poster – Quantum Optics, Technologies, and Optomechanics

Q 48.18: Poster

Mittwoch, 12. März 2025, 17:00–19:00, Tent

Mølmer-Sørensen Gates Robust to AC Shifts — •Erin Feldkemper — Institut für theoretische Physik, Leibniz Universität Hannover

In the past years the implementation of quantum gates has increased significantly. With the growing interest on fast and high-fidelity quantum gates, the interest in the optimization of these has grown as well. One of the key challenges is mitigating the AC Stark or Zeeman shift, which can arise in both laser-driven and microwave-driven gates, introducing errors which degrade the performance.

In this work, we focus on microwave-driven Mølmer-Sørensen gates and use the Magnus expansion in order to analyze the impact of the AC Zeeman shift on the gate performance. Starting from the full system Hamiltonian, we derived an effective Hamiltonian which includes the leading-order corrections induced by the AC Zeeman shift. This effective model was used for numerical simulations in order to validate the approximations made in the derivations and to gain insights into the gate*s fidelity and coherence properties. Here Kraus operators were implemented for the evaluation of the fidelity, while the von Neumann entropy was used to quantify entanglement and coherence degradation.

The control parameters can be optimized based on a cost function derived from the Magnus expansion. This optimization aims to further reduce the impact of the AC Zeeman shift and enhance gate fidelity.

Keywords: Mølmer-Sørensen Gates; AC Zeeman Shifts; Robustness; Quantum Gate; Optimal Control